[Tagging] length=

[Mike Thompson]

I have noticed a "length" tag used on some linear ways [1]. It seems
that this is redundant, as the length could be calculated from the
geometry itself.  It could also be the source of future errors should
someone split the way, for example to add more detailed tagging, such
as varying smoothness.

The length key does have a wiki page [2], but the page doesn't have
much content.  Perhaps it is only intended for nodes?

What do you think?  Should the length tag be used with ways and
relations where the length can be calculated from the geometry itself?
Am I missing something?

MIke

[1] https://www.openstreetmap.org/way/324078614
[2] http://wiki.openstreetmap.org/wiki/Key:length